posted by Prism Original SA post


Everything you know about space is wrong.

Infinite space; stars as flaming spheres of superheated plasma; movement through space as a balance of scientific forces, thrust providing acceleration and maneuverability; scientific fact backing up natural phenomena; life on other planets built along blocks of carbon or silicon elements.

Forget all that. It's wrong.

You can get out of the atmosphere on the back of a roc; fly between the planets through a breathable ocean of air; sail between the crystal spheres that surround the inhabited worlds on a river of magical energy; encounter roving mind flayers and beholders. The stars are living things in some areas, great bowls of fire in others, and pinpoints of light panted inside a sphere in others.

Welcome to the SPELLJAMMER™ universe.

Everything You Know About Space Is Wrong: A Fatal & Friends Spelljammer Exploration

So. This is Spelljammer.

Spelljammer is a supplement for AD&D 2nd Edition that has to do with space travel. But not regular old boring space travel, FANTASY space travel. Physics isn't invited to this party. It isn't a sci-fi modification; it really is just fantasy in space with sailing ships (sort of sailing ships, anyhow) travelling through the void (where it is a void). It advertised itself as a setting in its own right as well as a way to link highly disparate settings, if you wanted to go sail from one to another; the boxed set assumes that Oerth (Greyhawk), Toril (Forgotten Realms) and Krynn (Dragonlance) all exist as known worlds, though they don't all have significant regular contact with space.

Spelljammer was originally released as a boxed set including two books, The Concordance of Arcane Space and The Lorebook of the Void, a bunch of cardstock sheets showing deck plans of standard ships, and four poster-sized maps (including the legendary ship also named Spelljammer, a space citadel, a typical solar system, and a hex grid for tactical space battles; it also has some stand-up tokens for this). The Concordance of Arcane Space is the rulebook; the Lorebook of the Void is... well, a lorebook, though it's also where they put the monsters and some other odds and ends.

There were several more books released later in the Spelljammer line, including the Legend of Spelljammer (setting details), the War Captain's Companion (more detailed ship to ship combat rules), Lost Ships (more ships) and Practical Planetology (DM's guide to creating spelljamming settings), and a complete module set, among others. Like many of the campaign settings, it had its own novel series, which I haven't read, and its own computer game, which I have played. Spelljammer was discontinued before TSR was acquired by Wizards, and so there are no official 3rd (or 5th) Edition spelljamming rules. Spelljamming was mentioned in passing in 4th Edition as a way to planeswalk (planes-sail? planesjam?) but didn't have its own book. It's pretty much officially dead despite its cult popularity.

But right now we're just talking about the original 1989 boxed set, so don't worry about all that.

The foreword says to read the Concordance first, so we are, and I'll start there. I'm going to assume that people have a general idea about AD&D 2nd rules, and so rather than also go through the whole ruleset I'll mostly note where either Spelljammer varies or where the rules mean something different or noteworthy in the context of Spelljammer. I do know AD&D 2nd pretty well though, so if there are questions, I can answer them.

I also don't own a scanner so I can't scan the ship layout sheets. I'll try to find copies online but I make no guarantee as to their quality.

Coming up:

Chapter 1: Arcane Space
Probably The Only Rulebook I Have Ever Read With A Section Called 'Breathing In Space'

Where Up Is Down, Down Is Up, And Sometimes Both At Once

posted by Prism Original SA post

Since it seems to have gotten some chat, let's get right into

Everything You Know About Space Is Wrong: A Fatal & Friends Spelljammer Exploration

Chapter 1 (Concordance of Arcane Space): Arcane Space
Where Up Is Down, Down Is Up, And Sometimes Both At Once

Chapter 1 of the Concordance is a description of what space is like in Spelljammer. There are two major types of 'space': wildspace and phlogiston.

Wildspace is what you're probably thinking of when you think of 'space'. It's the big vacuum bit bwetween planets. (Well, most wildspace is vacuum; sometimes you go somewhere weird and it isn't.) It's what you travel through to get from planet to planet, or planet to moon, or asteroid base to crystal sphere. Phlogiston, on the other hand, is a multicoloured fluorescent gas, or something like gas. Every solar system is surrounded by a crystal sphere, which keeps the wildspace in and the phlogiston out.

Inside wildspace are celestial bodies - planets, suns, moons, weird shit. Most, but not all, have an atmosphere, and the size of an atmosphere is directly related to the size of a body. This actually applies to everything; if you are in wildspace, not on a ship, you are surrounded by an atmosphere too. When it's on something small, like a person or a ship, it's called an air envelope.

Outside wildspace is the phlogiston flow.

Air, or How To Breathe In Space

Air envelopes have about the same size in a given direction from the edge of the body as the body holding an air envelope. If you threw a rectangular block of metal that was 2 feet by 2 feet by 8 feet out, it would have an air envelope that was generally rectangular and about 6' x 6' x 24' with the block in the middle of it. This isn't very big, and people run out of useful air to breathe in 2d10 turns (a turn is 10 minutes) if all they have is their own air envelope, which is why you travel on ships.

Air is considered to be in one of three states: fresh, fouled, or deadly. Fresh air is fine. Fouled air is kind of stale and it's hard to exert yourself in; you get a -2 to attack rolls and ability checks in it. Deadly air isn't worth breathing. Ships have a complement maximum, and if you have that many people on board, air is good for about 4 months, then fouled for 4 more. If you go over, it runs out faster. Generally, bigger objects have more air, and really big objects don't need to worry about it.

The Curious Nature of Gravity

Air envelopes are held on by gravity. Everything has gravity! Planets have gravity. Ships have gravity. (Big) creatures have gravity. A human could walk on a dragon's back and stay there because of the dragon's gravity (though the dragon will probably object). The gravity field is the same size as the air envelope. Gravity only comes in one strength: Earth-level. If you're in a gravity field, you feel 1G in the direction of down. If you're not, you don't, and you float.

But the weird part is that gravity isn't 'in'. It is on planets or really big things; everything is pulled toward the center. But on smaller objects, it's more of a plane.

The gravity plane forms along the middle of any object that isn't big enough to be a planet (by Spelljammer rules, the smallest size of planet is 'less than ten miles across', but it doesn't say how big it has to be to have an 'in'; back when I ran Spelljammer I made it about a mile, because the legendary ship Spelljammer is 3100' long and acts like a ship, not a planet). It attracts from both the top and the bottom so you can stand on the bottom of a ship just fine. If you drop something off the side, it falls past the plane, then falls upwards, and oscillates around a bit until it ends up 'stuck' more or less on the plane. This is apparently done to amuse new passengers. Things that have fallen to the gravity plane tend to drift outward over time, so eventually they will exit the gravity field unless retrieved.

When two ship-scale gravity fields touch, you use whichever you're closer to. You can jump ship to ship and change which way is 'down' halfway through the jump. When the objects are actually in contact, though - say, by ramming - the bigger object wins, and sets 'down' for all smaller objects in its field. This means you can interfere with other ships' gravity by ramming at odd angles, if they're smaller than you, and cause chaos on their deck. Because of this, ships are generally built with a definite 'down' in case they get subject to someone else's gravity (or try to land) and also try to mostly match other ships in a battle's orientation.

Things that are not in any gravity field but their own are weightless and move as you'd expect a weightless body to move. They don't go very quickly, and keep moving once they start moving, until they intersect a gravity field.


Ships travel through wildspace with a spelljamming helm, which turns magic power into thrust. A spellcaster puts on the helm and can drive the ship. We'll get to rules on that later, but for now, just know that while they're powering the ship they're not really useful for anything else, and more powerful spellcasters make you faster in tactical combat (long-range travel is about the same regardless because the real advantage is acceleration).

Ships generally travel through the phlogiston on currents. A spelljammer helm is used for steering.

Phlogiston: The Fifth Element

Outside wildspace is the phlogiston, which is both the term for the gas-like medium and the place where the phlogiston is.

Phlogiston forms natural 'flows' and 'rivers', which you can 'sail' on. You can speed up by going deeper into the flow, or slow down by rising out of it. Sails, fins, and similar ship accessories speed you up because you can catch more of the flow. Gravity in the phlogiston works the same way as in wildspace, though there are fewer large objects other than ships.

Phlogiston is also flammable and explosive. Extremely so. Any flame exposed to phlogiston blows up. Trying to use fire attack spells, gunpowder, or even a cooking stove is a good way to explode your face. (And using a fire attack spell does have it blow up in your face; you can't target it anywhere else.) Fortunately, phlogiston glows, so you don't need light to see by, but I imagine the food gets boring after a while.

Running out of air in the phlogiston doesn't kill a character. Instead, you enter suspended animation, turning grey and stony until you end up in air again. A current will probably push you to a sphere eventually. (Slavers love finding people in the phlogiston.)

Crystal Spheres

And between the wildspace and the phlogiston are the crystal spheres, or crystal shells.

Crystal spheres are usually about twice as big in radius as the last planet in a solar system, but may be smaller (say, only half again). They're really, really big, and look flat when you sail up to one. The crystal spheres are universally an unbreakable, dark, ceramic material. Some legends say that the gods put them there to protect their worlds from phlogiston; others say that they were put there to keep the gods in check.

Crystal spheres are unbreakably solid. No item or magic is known that can break one, up to and including direct interference by a deity. Unlike everything else big in space, they don't have a gravity field. There are five ways through a crystal sphere.

That's it. Nothing else affects a crystal sphere.

More importantly, crystal spheres are the outer limits of a region's deity's powers. Magic that summons things from other planes or opens extradimensional pockets just doesn't work once you're past a crystal sphere, and this includes clerics gaining powerful spells (defined as 'level 3+') from their gods. While there is a relatively simple spell clerics can use to recharge themselves, summoning or extradimensional pockets are basically inoperable. (Wish will let you get into extradimensional storage. Nothing will help with summoning.)

Odds and Ends

Just a few things that are best handled with bullet points.

Coming up next:

Chapter 2: AD&D Rules... IN SPACE!

Nobody Likes You Anyway, Clerics

posted by Prism Original SA post

Everything You Know About Space Is Wrong: A Fatal & Friends Spelljammer Exploration

Chapter 2 (Concordance of Arcane Space): AD&D Rules In Space
Nobody Likes You Anyway, Clerics

Chapter 2 is AD&D Rules In Space. As it helpfully tells us, most rules work exactly as they usually do, but there are some changes, additions, and new options. This is a summary chapter, as some of the details are gone through more in depth in later chapters, as are brand-new rules like ship-to-ship combat and piloting.

Ability Scores

No change. Literally none. The paragraph here starts with 'AD&D ability scores are unaffected in play in space.' and could end there.

Character Races in Space

All the usual races from various worlds can go to space and have the same stats as they do wherever they came from, including level restrictions on classes and special abilities. This means you can mix and match from different settings.

There's also a new race, the spacefaring lizard men. Lizard men are... uh, they're lizard men, you know what they are. Humanoid reptiles, claws, scales, not necessarily real bright. We'll get to their theme in the Lorebook of the Void, but the brief summary is that they were originally brought to space as slaves and figured out that lizardmen that hatched closer to the sun were generally smarter, so now they go out of their way to do that.

Lizardmen have a minimum strength of 8 and constitution of 6, and can't have 18 Intelligence (even the spaceborne ones). They have a natural AC of 5 because they have thick, scaly hides, and don't get any benefit from armour unless it's better than that; they also don't get an AC bonus from Dexterity. Lizardmen can be fighters (maximum level 12), thieves (maximum level 11), or clerics (maximum level 7), but cannot multiclass.

Lizardmen have natural attacks: two claws at 1d2 and one tail-slap at 1d6. They can wield weapons, and 'dual-wield' their weapon and their tail with all the usual penalties for dual-wielding. There is nothing that says they can't do this with a two-handed weapon. Lizardmen who aren't wearing armour can swim very quickly, but they're otherwise on the slow side. They don't breathe water.

Character Classes in Space

All character classes in the PHB exist in space.

Special Races and Classes


Many worlds have special player character classes and/or races: samurai, hengeyokai, minotaurs, and other 'specialty' classes and races unique to particular campaigns. These classes function normally in wildspace, within the void's physical limitations. They are not normally used for player characters in space.

Why would you not let someone play a world-specific class or race? I mean, that's part of the fun of Spelljammer, right? Didn't we just go over this in Character Races in Space?

Ah well.

Magic Use in Space

Short form: clerics are fucked way more than wizards.

Clerics are fine in the crystal sphere they came from, but because you can't contact other planes in the phlogiston, they can't get direct contact with their deity or servants thereof to regain spells. They can use any spells they have, but they can't regain spells over 2nd level without getting around that restriction.

Similarly, clerics in a crystal sphere where their deity is not worshipped also cannot regain high-level spells. Gods have power in a given shell if they have established worshippers or an organized church in that system.

Many standard deities are worshipped in multiple crystal spheres. Additionally, there are also some space faiths that have a presence in many spheres.

Calling-style spells don't work if there's nothing to call around. If you cast, say, call animals while in the process of flying from the planet to the moon, you aren't getting anything because there are no animals there.

Any spell that contacts another plane doesn't work at all in the phlogiston, so you can't summon elementals or cast contact other plane or anything else you might be thinking of. They work fine in any crystal sphere though. Similarly, planar or dimensional travel doesn't work in the phlogiston, but work normally in any crystal sphere. This includes accessing extradimensional pockets, so your bags of holding are just regular bags in the flow.

Fire spells work normally in wildspace inside air pockets.

Here's one of the first conflicts: This section claims that instantaneous fire creation spells work in the vacuum too, so you can fireball space but not light things on fire in the void with it. The section on magic later explicitly calls out fireball as not being capable of detonating in the void, though. Which one is correct? Probably the one where it doesn't work.

Fire spells work too well in the phlogiston and do triple damage in triple the area of effect, always centered on the caster. If you are immune to fire, presumably you can do some stuff with this.

New Spells
Just a quick summary of each spell.

Create/destroy air (Priest 1): Guess. It's enough for one person for every two levels of the caster and will refresh their bubble if they're in the void; you can also use it to get an extra saving throw against foul gases. Destroy air actually makes it fouled, not deadly or vacuum. It doesn't make enough air to refresh or damage a ship's air envelope.
Locate portal (Wizard 2): Locates the closest natural portal on a crystal sphere. It has to be cast within 100 yards of a crystal sphere (so you have to drive right up to it and stop) but it detects across the entire sphere; generally the portals for a normal-sized ship are between 2 and 20 days' flight away.
Contact home power (Priest 2): When cast in a crystal sphere, makes the cleric able to regain spells as if their deity was worshipped there for one week. Still doesn't work in the phlogiston and there is no way for a cleric to ever regain spells above level 2 there. At least this is only level 2 so you can always memorize it.
Detect powers (Priest 2): Lets you know which deities have power in the sphere you're in, and especially if your deity has power here. If you're not in a sphere that the DM already decided exactly who is worshipped there, yours has a one in ten chance of being worshipped (and thus you can regain spells normally), and a four in ten chance of a related power on good terms being available, in which case you can regain spells once you talk to their priests.
Chill fire (Wizard 3): Makes phlogiston less flammable (not non-flammable) in a 40 yard radius for 10 minutes per level. Magic fire does normal damage at normal area of effect, but still centers on the caster. Doesn't say precisely what it does to regular fires, so I presume they just act normally.
Enhance/reduce rating (Wizard 3): Makes a spelljammer helm work better or worse for 1d4 + level minutes.
Softwood (Priest 4): Surrounds a person in soft wood. It's a life support bubble. It flakes away in breatheable air over about a half hour, but if you put them somewhere there is no air, it lasts indefinitely.
Create portal (Wizard 5): Makes part of a crystal sphere intangible and thus usable as a portal for a couple hours.
Enhance/reduce maneuverability (Wizard 5): Makes a ship more or less maneuverable for 1d4 + level minutes.
Create minor helm (Priest 5, Wizard 6): Makes a temporary (1 week/level) minor spelljamming helm. Can't be made permanent with permanency.
Create major helm (Wizard 7): Like create minor helm, except it only lasts one day per level but counts as a major helm. There is no priestly equivalent.

And that's it for adjustments to rules we already know. Next time it's

Chapter 3: Ships of Wildspace
Ship rules and stats!